Shares in Credit Suisse Group (CS) fell Friday on fears that its private bank will be hit by wealthy clients withdrawing funds because of growing pressure on Swiss banking secrecy.

At 0834 GMT, the stock was CHF0.71 lower, or down 1.6%, at CHF44.07, extending a 7.4% fall from the previous day. Credit Suisse fell more than rival private banks such as UBS AG (UBS) and the Stoxx Europe 600 bank index, which was 0.9% lower.

Zurich-based Credit Suisse hit back at repeated newspaper reports that data on its clients might be on a compact disc which is being offered for sale to Germany by an unknown informant. German officials have signaled they are prepared to buy the data as part of a crackdown on alleged tax offenders, a move which has elicited indignation from Swiss officials.

"We have no indication at all that Credit Suisse is involved. Credit Suisse adheres to all rules and regulations where it does business and takes the privacy of its clients very seriously," a spokesman for the Zurich-based bank reiterated Friday.

The informant hasn't been identified, but German officials said he requested EUR2.5 million for information on the accounts held by some 1,500 potential German tax evaders.

Analysts said Credit Suisse could suffer outflows despite not being definitively linked to the stolen data.

"Ultimately, it doesn't matter whether they are involved or not. Basically, if someone has undeclared funds at Credit Suisse, and is convinced banking secrecy cannot be maintained by the Swiss government, then probably funds will be withdrawn and placed elsewhere," Kepler Capital Markets analyst Dirk Becker said. He rated Credit Suisse at buy with an CHF80 target price.

Germany has traditionally been a major market for Swiss private banks, partly because the two countries share a border and a common language. Independent brokerage Helvea estimates that wealthy Germans hold roughly 280.6 billion Swiss francs ($262.2 billion) in Swiss private banks, the overwhelming majority--over two-thirds--estimated by Helvea as undeclared to German tax authorities.

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Other Swiss banks have also sought to deflect the link to the stolen data. Earlier Friday, Julius Baer Group AG (BAER.VX) said it had no indication of its involvement, while UBS Friday said nothing had changed since it released a statement earlier this week saying it wasn't aware of any information and that a link to UBS is speculation for the moment.